Housing parts comprising a lubricant reservoir are used for installation into land, air, water or underwater vehicles and serve there for receiving movable mechanical components such as particularly transmissions or rotary actuators, wherein these movable components are bathed in the lubricating fluid accommodated in the lubricant reservoir of the housing part, whereby they are lubricated and also cooled in a given case.
From DE 101 53 151 A1 a system and a method for the maintenance of actuators of aircraft by using sensors for measuring the humidity content in the actuators are known.